How does this box work?

[bunkerking09 10+ year member]

A box like this...

http://www.caraudio.com/forum/showthread.php?p=5121342&posted=1#post5121342

I'm looking to design one for (4) 8's in a standard cab. Is it just considered a bandpass? How do you calculate tuning? Net volume? Etc.

Click to read more...

 

[SRim23 5,000+ posts]

why not PM him and ask him?

 

[bunkerking09 10+ year member]

its not just his box, i mean boxes like that in general.

i also thought this would be a useful thread, i've never seen anyone ask about it, all the talk is about regular ported enclosures. This is unique.

 

[ngsm13 5,000+ posts]

The front looks like it's just a beauty panel though it may act as semi-bandpass...

nG

 

[Immacomputer 10+ year member]

Not bandpass but more of an expanding transmission line with definite ported properties.

To get an idea of the response, you could start not considering the chamber where the subs fire into and just consider it a ported enclosure. You can find a net volume and tuning there but those terms are going to be slightly meaningless as the impedance curve is going to be pretty different.

A good idea to finding the lower cutoff is to take the length from behind the subs to opening of the enclosure and then take the ratio of cross sectional area in the opening to the total cross sectional area right behind the subs. Apply that ratio and length to Martin J. King's PDF file that says "Alignment Tables" on page 10. Your lower cutoff will be around a 1/2 an octave below that point. The longer the distance between you and the opening of the enclosure and the lower your bottom end will go, basically.

That will give you an idea of about how it will respond. The calculated ported figures won't really mean much though and you probably won't have lowest cone movement at "tuning".